projects / deliverable / linux.git / blame
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|---|---|---|
| 5377d91f MH |
1 | .. -*- coding: utf-8; mode: rst -*- |
| 2 | ||
| 3 | .. _FE_SET_VOLTAGE: | |
| 4 | ||
| 5 | ******************** | |
| 6 | ioctl FE_SET_VOLTAGE | |
| 7 | ******************** | |
| 8 | ||
| 9 | *man FE_SET_VOLTAGE(2)* | |
| 10 | ||
| 11 | Allow setting the DC level sent to the antenna subsystem. | |
| 12 | ||
| 13 | ||
| 14 | Synopsis | |
| 15 | ======== | |
| 16 | ||
| 17 | .. c:function:: int ioctl( int fd, int request, enum fe_sec_voltage *voltage ) | |
| 18 | ||
| 19 | Arguments | |
| 20 | ========= | |
| 21 | ||
| 22 | ``fd`` | |
| 23 | File descriptor returned by :ref:`open() <frontend_f_open>`. | |
| 24 | ||
| 25 | ``request`` | |
| 26 | FE_SET_VOLTAGE | |
| 27 | ||
| 28 | ``voltage`` | |
| 29 | pointer to enum :ref:`fe_sec_voltage <fe-sec-voltage>` | |
| 30 | ||
| 31 | Valid values are described at enum | |
| 32 | :ref:`fe_sec_voltage <fe-sec-voltage>`. | |
| 33 | ||
| 34 | ||
| 35 | Description | |
| 36 | =========== | |
| 37 | ||
| 38 | This ioctl allows to set the DC voltage level sent through the antenna | |
| 39 | cable to 13V, 18V or off. | |
| 40 | ||
| 41 | Usually, a satellite antenna subsystems require that the digital TV | |
| 42 | device to send a DC voltage to feed power to the LNBf. Depending on the | |
| 43 | LNBf type, the polarization or the intermediate frequency (IF) of the | |
| 44 | LNBf can controlled by the voltage level. Other devices (for example, | |
| 45 | the ones that implement DISEqC and multipoint LNBf's don't need to | |
| 46 | control the voltage level, provided that either 13V or 18V is sent to | |
| 47 | power up the LNBf. | |
| 48 | ||
| 49 | NOTE: if more than one device is connected to the same antenna, setting | |
| 50 | a voltage level may interfere on other devices, as they may lose the | |
| 51 | capability of setting polarization or IF. So, on those cases, setting | |
| 52 | the voltage to SEC_VOLTAGE_OFF while the device is not is used is | |
| 53 | recommended. | |
| 54 | ||
| 55 | RETURN VALUE | |
| 56 | ||
| 57 | On success 0 is returned, on error -1 and the ``errno`` variable is set | |
| 58 | appropriately. The generic error codes are described at the | |
| 59 | :ref:`Generic Error Codes <gen-errors>` chapter. | |
| 60 | ||
| 61 | ||
| 62 | .. ------------------------------------------------------------------------------ | |
| 63 | .. This file was automatically converted from DocBook-XML with the dbxml | |
| 64 | .. library (https://github.com/return42/sphkerneldoc). The origin XML comes | |
| 65 | .. from the linux kernel, refer to: | |
| 66 | .. | |
| 67 | .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook | |
| 68 | .. ------------------------------------------------------------------------------ |